SIX6

Chr 14AR

SIX homeobox 6

Also known as: MCOPCT2, ODRMD, OPTX2, Six9

SIX6 encodes a homeobox transcription factor involved in eye development. Biallelic mutations cause optic disc anomalies with retinal and/or macular dystrophy, inherited in an autosomal recessive pattern. The gene shows moderate constraint against loss-of-function variants (LOEUF 0.595), consistent with its role in ocular development.

OMIMResearchSummary from RefSeq, OMIM, UniProt
LOFmechanismARLOEUF 0.591 OMIM phenotype
Clinical SummarySIX6
Population Constraint (gnomAD)
Moderately constrained gene (pLI 0.52) — some intolerance to loss-of-function variants.
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ClinVar Variants
23 unique Pathogenic / Likely Pathogenic· 87 VUS of 177 total submissions
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Clinical Trials
4 active or recruiting trials — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Moderate LoF intolerance
LoF Constraint
0.59LOEUF
pLI 0.518
Z-score 2.44
OE 0.19 (0.080.59)
Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint
0.71Z-score
OE missense 0.83 (0.710.97)
117 obs / 140.8 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios
LoF OE0.19 (0.080.59)
00.351.4
Missense OE0.83 (0.710.97)
00.61.4
Synonymous OE0.85
01.21.6
LoF obs/exp: 2 / 10.6Missense obs/exp: 117 / 140.8Syn Z: 0.94
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
strongSIX6-related MAC spectrumLOFAR
limitedSIX6-related microphthalmia, isolated, with cataractOTHERAD
DN
0.6357th %ile
GOF
0.5367th %ile
LOF
0.51top 25%

The highest-scoring mechanism for this gene is dominant-negative.

DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

177 submitted variants in ClinVar

Classification Summary

Pathogenic15
Likely Pathogenic8
VUS87
Likely Benign52
Benign5
Conflicting9
15
Pathogenic
8
Likely Pathogenic
87
VUS
52
Likely Benign
5
Benign
9
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
1
2
12
0
15
Likely Pathogenic
4
1
3
0
8
VUS
5
61
18
3
87
Likely Benign
0
1
9
42
52
Benign
0
1
3
1
5
Conflicting
9
Total10664546176

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

Protein Context — Lollipop Plot

SIX6 · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

3D Protein StructureAlphaFold
Clinical Literature
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